Abstract

Applications in quantum information processing and photondetectors are stimulating a race to produce the highest possible quality factor on-chip superconducting microwaveresonators. We have tested the surface-dominated loss hypothesis by systematically studying the role of geometrical parameters on the internal quality factors of compact resonators patterned in Nb on sapphire. Their single-photon internal quality factors were found to increase with the distance between capacitor fingers, the width of the capacitor fingers, and the resonator impedance. Quality factors were improved from 210 000 to 500 000 at T = 200 mK. All of these results are consistent with our starting hypothesis.

Received 27 March 2012Accepted 16 April 2012Published online 07 May 2012

Acknowledgments:

The authors thank Danielle Braje at MIT-LL for an independent measurement of our resonators. This research was supported by IARPA under Grant No. W911NF-09-1-0369 and ARO under Grant No. W911NF-09-1-0514.